02-band-limited-oscs.py - Oscillators whose spectrum is kept under the Nyquist frequency.

This tutorial presents an object (misnamed LFO but it’s too late to change its name!) that implements various band-limited waveforms. A band-limited signal is a signal that none of its partials exceeds the nyquist frequency (sr/2).

The LFO object, despite its name, can be use as a standard oscillator, with very high fundamental frequencies. At lower frequencies (below 20 Hz) this object will give a true LFO with various shapes.

The “type” slider in the controller window lets choose between these particular waveforms:

  1. Saw up (default)

  2. Saw down

  3. Square

  4. Triangle

  5. Pulse

  6. Bipolar pulse

  7. Sample and hold

  8. Modulated Sine

from pyo import *

s = Server().boot()

# Sets fundamental frequency.
freq = 187.5

# LFO applied to the `sharp` attribute
lfo = Sine(0.2, mul=0.5, add=0.5)

# Various band-limited waveforms
osc = LFO(freq=freq, sharp=lfo, mul=0.4).out()

# Displays the waveform
sc = Scope(osc)

# Displays the spectrum contents
sp = Spectrum(osc)